Recently introduced qacA/B genes in Staphylococcus epidermidis do not increase chlorhexidine MIC/MBC

TY - JOUR

T1 - Recently introduced qacA/B genes in Staphylococcus epidermidis do not increase chlorhexidine MIC/MBC

AU - Skovgaard, Sissel

AU - Larsen, Marianne Halberg

AU - Nielsen, Lene Nørby

AU - Skov, Robert Leo

AU - Wong, Christian

AU - Westh, Henrik T.

AU - Ingmer, Hanne

PY - 2013/10

Y1 - 2013/10

N2 - Objectives:Chlorhexidine is used as a disinfectant to prevent surgical infections. Recently, studies have indicated that chlorhexidine usagehas selected methicillin-resistant Staphylococcus aureus strains that aretolerant to chlorhexidine and that this may be related to the presence of the qacA/B-encoded efflux pumps. Here, we evaluated if high-level exposure to chlorhexidine selects for tolerant colonizing Staphylococcus epidermidis and we addressed the consequences of long-term exposure to chlorhexidine.Methods: Chlorhexidine susceptibility and carriage of qacA/Bwas determined for colonizing S. epidermidis isolated fromscrub nurses heavily exposed to chlorhexidine andwere compared with isolates fromnon-users of chlorhexidine hand rubs. S. epidermidis blood isolates from the 1960s, before the wider introduction of chlorhexidine to the market, were also tested and compared with recently collected S. epidermidis blood isolates. Results:There was no correlation between the use of chlorhexidine in scrub nurses and the presence of qacA/B genes in S. epidermidis isolates or increased MICs/MBCs of chlorhexidine for S. epidermidis isolates. While 55% of current blood isolates harboured the qacA/B genes, none of the 33 historical S. epidermidis isolates did, although their MICs and MBCs of chlorhexidine were comparable to those for current isolates.Conclusions: Chlorhexidine used as a hand rub does not select for S. epidermidis isolates with increased MICs or MBCs of chlorhexidine. However, the absence of qacA/B genes in S. epidermidis isolates obtained in the 1960s suggests that long-term use of biocides like chlorhexidine or related compoundsmayselect for the presence of qacA/B genes.

AB - Objectives:Chlorhexidine is used as a disinfectant to prevent surgical infections. Recently, studies have indicated that chlorhexidine usagehas selected methicillin-resistant Staphylococcus aureus strains that aretolerant to chlorhexidine and that this may be related to the presence of the qacA/B-encoded efflux pumps. Here, we evaluated if high-level exposure to chlorhexidine selects for tolerant colonizing Staphylococcus epidermidis and we addressed the consequences of long-term exposure to chlorhexidine.Methods: Chlorhexidine susceptibility and carriage of qacA/Bwas determined for colonizing S. epidermidis isolated fromscrub nurses heavily exposed to chlorhexidine andwere compared with isolates fromnon-users of chlorhexidine hand rubs. S. epidermidis blood isolates from the 1960s, before the wider introduction of chlorhexidine to the market, were also tested and compared with recently collected S. epidermidis blood isolates. Results:There was no correlation between the use of chlorhexidine in scrub nurses and the presence of qacA/B genes in S. epidermidis isolates or increased MICs/MBCs of chlorhexidine for S. epidermidis isolates. While 55% of current blood isolates harboured the qacA/B genes, none of the 33 historical S. epidermidis isolates did, although their MICs and MBCs of chlorhexidine were comparable to those for current isolates.Conclusions: Chlorhexidine used as a hand rub does not select for S. epidermidis isolates with increased MICs or MBCs of chlorhexidine. However, the absence of qacA/B genes in S. epidermidis isolates obtained in the 1960s suggests that long-term use of biocides like chlorhexidine or related compoundsmayselect for the presence of qacA/B genes.

U2 - 10.1093/jac/dkt182

DO - 10.1093/jac/dkt182

M3 - Journal article

C2 - 23739538

SN - 0305-7453

VL - 68

SP - 2226

EP - 2233

JO - The Journal of antimicrobial chemotherapy

JF - The Journal of antimicrobial chemotherapy

IS - 10

ER -